A surreptitious photographing prevention device described in PTL 1 includes a light source device, a projection lens system, and a control unit. The light source device is configured of infrared light and generates interference light that degrades a video content. The lens system projects the interference light emitted from the light source device toward a screen. The control unit controls the light source device so as to generate the interference light at a predetermined time interval or at an irregular time interval. The surreptitious photographing prevention device superimposes and projects temporally and intermittently the generated interference light on the video content to be projected on the screen.
However, even when there is a portion in the video content for which confirmation is desired, the interference light may be superimposed on the portion to reduce a visibility and it may be difficult to confirm the portion. For example, when the interference light is superimposed on the entire subject including a person, it may be impossible to grasp the person at all.
An object of the present disclosure is to reduce the visibility by limiting to a part of image regions in a captured image.